title: Increased expression of NGFI-A mRNA in the rat striatum following burst stimulation of the medial forebrain bundle.
abstract: Using in situ hybridization, we examined the mRNA expression for several immediate early genes in dopamine-innervated brain areas following electrical burst vs. regular stimulation of the medial forebrain bundle in anaesthetized rats. Two hours after 5 Hz burst stimulation, the expression of the nerve growth factor-inducible clone A (NGFI-A) mRNA was increased in the medial part of the striatum. This increase was prevented by pretreatment with the dopamine-D1 receptor antagonist, SCH23390 (0.1 mg/kg i.p.). After 8 Hz burst stimulation, NGFI-A mRNA expression was increased in the medial, central and lateral parts of the striatum. Induction occurred predominantly in cells expressing mRNAs for the dopamine-D1 receptor, substance P and dopamine and cAMP-regulated phosphoprotein (DARP-32). Regular stimulation had no effect on NGFI-A mRNA expression. The induction of NGFI-A was related to the levels of dopamine released by burst or regular stimulation as demonstrated with in vivo amperometry. Two hours after stimulation, the expression of none of the other genes studied was altered. One hour after 8 Hz burst stimulation, the expression of NGFI-A, NGFI-B and jun-B mRNAs was increased in the striatum and that of NGFI-A, NGFI-B, c-fos, fos-B and jun-B mRNAs was variably increased in the nucleus accumbens and lateral septum. These results provide additional support for the physiological importance of burst firing activity in midbrain dopamine neurons for the activation of their target cells. They demonstrate a spatial and temporal specificity as regards the brain region, the gene activated, the receptor involved and the phenotype of the cells affected.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Chergui
authors.forename: P
authors.initials: P
authors.lastname: Svenningsson
authors.forename: G G
authors.initials: GG
authors.lastname: Nomikos
authors.forename: F
authors.initials: F
authors.lastname: Gonon
authors.forename: B B
authors.initials: BB
authors.lastname: Fredholm
authors.forename: T H
authors.initials: TH
authors.lastname: Svennson
mesh_terms: D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004298:Dopamine / Q000378:metabolism; D051766:Early Growth Response Protein 1; D004558:Electric Stimulation; D004594:Electrophysiology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D017781:Genes, Immediate-Early / Q000187:drug effects; D017874:Immediate-Early Proteins; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D008297:Male; D008474:Medial Forebrain Bundle / Q000502:physiology*; D017072:Neostriatum / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000096:biosynthesis; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D014157:Transcription Factors; D004298:Dopamine